We note that the notion of a relativistically boosted Cooper pair has previously been studied with respect to the entanglement structure of the constituent fermions [1]}, [2]}. These studies concluded that an isotropic \(s\) -wave spin singlet Cooper pair would acquire spin triplet components under a Lorentz boost due to Wigner rotation [3]}. It is not obvious how this result compares to the relativistic theory of superconductivity constructed above based on [4]}, [5]}, [6]}, [7]}, as for example the spin singlet pairing correlation function (REF ) is invariant under Lorentz transformations and does not acquire triplet components (recall that spin triplet pairing manifests as even parity under matrix transposition). With respect to the conclusions of [1]}, [2]} where a boosted spin singlet transforms into a pair with singlet and triplet components, our work presented above can be said to occur in the spin singlet projection of the transformed pair, and thus our conclusions regarding the emergence of an odd-frequency channel are valid regardless.
